In performing color printing with image recording apparatuses such as a color electrophotographic printer (laser printer), desired colors are reproduced by superimposing a plurality of colors such as CMYK (Cyan, Magenta, Yellow, and Black). However, there occur various unevenness and allocation errors in a mechanism conveying a recording medium, thereby causing color shift in which the printing positions of a plurality of superimposed colors are shifted. Japanese Patent Application Publication No. 2001-337504 discloses a method of correcting color shift for each color for preventing such a color shift.